PDF(Pubmed)
Abstract：
Some citrus orchards in China often experience nitrogen (N) deficiency. For the first time, targeted metabolomics was used to examine N-deficient effects on hormones in sweet orange (Citrus sinensis (L.) Osbeck cv. Xuegan) leaves and roots. The purpose was to validate the hypothesis that hormones play a role in N deficiency tolerance by regulating root/shoot dry weight ratio (R/S), root system architecture (RSA), and leaf and root senescence. N deficiency-induced decreases in gibberellins and indole-3-acetic acid (IAA) levels and increases in cis(+)-12-oxophytodienoic acid (OPDA) levels, ethylene production, and salicylic acid (SA) biosynthesis might contribute to reduced growth and accelerated senescence in leaves. The increased ethylene formation in N-deficient leaves might be caused by increased 1-aminocyclopropanecarboxylic acid and OPDA and decreased abscisic acid (ABA). N deficiency increased R/S, altered RSA, and delayed root senescence by lowering cytokinins, jasmonic acid, OPDA, and ABA levels and ethylene and SA biosynthesis, increasing 5-deoxystrigol levels, and maintaining IAA and gibberellin homeostasis. The unchanged IAA concentration in N-deficient roots involved increased leaf-to-root IAA transport. The different responses of leaf and root hormones to N deficiency might be involved in the regulation of R/S, RSA, and leaf and root senescence, thus improving N use efficiency, N remobilization efficiency, and the ability to acquire N, and hence conferring N deficiency tolerance.
摘要：
中国的一些柑橘园经常经历氮（N）缺乏。第一次,靶向代谢组学用于检查甜橙中N缺乏对激素的影响（Citrussinensis（L.)奥斯贝克简历。雪根）叶子和根。目的是验证以下假设：激素通过调节根/茎干重比（R/S）在N缺乏耐受性中起作用。根系统架构(RSA)，叶和根衰老。N缺乏引起的赤霉素和吲哚-3-乙酸（IAA）水平降低，顺式（）-12-氧代双烯酸（OPDA）水平升高，乙烯生产，水杨酸（SA）的生物合成可能导致叶片生长减少和衰老加速。缺氮叶片中乙烯形成的增加可能是由1-氨基环丙烷羧酸和OPDA增加以及脱落酸（ABA）减少引起的。N缺乏增加R/S，改变了RSA,通过降低细胞分裂素延迟根衰老，茉莉酸,OPDA,和ABA水平以及乙烯和SA的生物合成，增加5-脱氧str的水平，维持IAA和赤霉素的稳态。N缺乏根中IAA浓度不变，涉及叶-根IAA转运增加。叶片和根系激素对N缺乏的不同反应可能参与了R/S的调节,RSA,叶和根衰老，从而提高了N的使用效率，N的再动员效率，以及获得N的能力，从而赋予氮缺乏耐受性。
